Simulation of mixed bond graphs and block diagrams on personal computers using TUTSIM

The TUTSIM simulation program for continuous dynamic systems accepts (nonlinear) block diagrams, bond graphs or a free mix of both. The simulation is “hands on” interactive, providing a direct contact with the model. The implementation of the program on existing personal computers (Apple II, IBM PC) requires small memory size and has a high computational speed, due to its assembler source code. A slower FORTRAN CP/M version is available. It is shown how bond graphs can be used as an input language. An example using bond graphs as a modelling tool is presented

Microbial manipulation of host sex determination

A recent study in the lepidopteran Ostrinia scapulalis shows that endosymbionts can actively manipulate the sex determination mechanism of their host. Wolbachia bacteria alter the sex-specific splicing of the doublesex master switch gene. In ZZ males of this female heterogametic system, the female isoform of doublesex is produced in the presence of the bacteria. The effect is a lethal feminization of genotypic males. Curing of ZW females leads to males that die, indicating that the bacteria have an obligate role in proper sex determination and development of their host. Microbial intervention with host sex determination may be a driving force behind the evolutionary turnover of sex determination mechanisms

An Extraordinary Sex Determination Mechanism in a Book Louse

In this commentary, Leo Beukeboom considers the findings of Hodson et al. in this issue of GENETICS, and their discovery of an unusual sex determination mechanism in a book louse, a little-studied group of insects

Mood and representations of behaviour: The how and why

Based on the idea that mood helps to tune cognitive processes to current demands, we hypothesised that mood should influence the abstraction level in which people think about behaviour, and that such mood - induced differences in cognitive attention should be manifested in behaviour descriptions. In this study, participants re-described a number of daily behaviours in their own words after a mood manipulation. As predicted, people in a positive mood were more likely to re-describe behaviours in general why terms, whereas people in a negative mood were relatively more likely to re-describe behaviours in specific how terms. The findings are discussed with respect to the role of mood in processes of behaviour regulation.© 2005 Psychology Press Ltd